#include <iostream>
#include <fstream>
#define DIM 1000005
#include <algorithm>
using namespace std;
ifstream f("trapez.in");
ofstream g("trapez.out");
struct punct
{
    double x,y;
}b[1001];
double a[DIM];
int n,nr;
void solve()
{
    f>>n;
    for(int i=1;i<=n;i++)
    {
        f>>b[i].x>>b[i].y;
        for(int j=i-1;j>=1;j--)
            a[++nr]=double((b[i].y-b[j].y)/(b[i].x-b[j].x));
    }
    sort(a+1,a+nr+1);
    int k=1; long long sol=0;
    for(int i=2;i<=nr;i++)
        if(a[i]==a[i-1])
            ++k;
        else
        {
            sol+=k*(k-1)/2;
            k=1;
        }
    g<<sol;
}
int main()
{
    solve();
    return 0;
}